Present day manufacturing for semiconductor electronics, solar cells, and other technology relies on ion implanter systems for doping or otherwise modifying silicon and other types of substrates. One type of ion implanter system performs the doping by generating an ion beam and directing it toward a substrate so that the ions come to rest beneath the substrate surface. In many applications, ion beams having a defined shape and ion beam area such as a spot beam or ribbon beam are scanned over a substrate to implant a species into a substrate area that is larger than the ion beam area. The substrate may be scanned with respect to a stationary beam or both substrate and beam may be scanned with respect to one another. In any of these circumstances many applications require that a substrate be implanted uniformly over a large portion of the substrate. Unfortunately, certain non-uniformities may result during the implant process.
Certain non-uniformities may be produced by the ion beam during the implant process. One type of non-uniformity is the spread of angles of incidence of a nominally parallel ion beam. In some cases this spread of angles of incidence may track systematically across a substrate such that the angle of incidence toward one side is different than that toward another side. Beamline ion implantation apparatus often treat an ion beam by shaping, deflecting, accelerating, and decelerating ions through various components over the beam path. In many systems, even after “collimation” of an ion beam at final stages before incidence on a substrate, the vertical angle spread of ions across a substrate may be, for example, between about 0.5 to 1.0°. Even small differences in angles of incidence may have large effects on implant process uniformity. It is with respect to these and other considerations that the present improvements have been needed.